pollution

There’s a big to-do going on right now in Germany over particulate-matter air pollution. Stuttgart, Germany’s “motor city” and one of Dante’s seven circles of Hell during rush hour, had the nation’s first-ever air pollution alert last year. Cities are considering banning older diesel cars outright. So far, Stuttgart’s no-driving days have been voluntary, and the change of the seasons has helped a lot as well. But that doesn’t mean there’s not a problem.

But how big is the issue? And where is it localized? Or is particulate pollution localized at all? These questions would benefit from a distributed network of particulate sensors, and the OK Lab in Stuttgart has put together a simple project(translated here) to get a lot of networked sensors out into the wild, on the cheap.

The basic build is an ESP8266 with an SDS011 particulate sensor attached, with a temperature and humidity sensor if you’re feeling fancy. The suggested housing is very clever: two 90° PVC pipe segments to keep the rain out but let the dust in through a small pipe. The firmware that they supply takes care of getting the device online through your home WiFi. Once you have it running, shoot them an e-mail and you’re online. If you want help, swing by the shackspace.

We love these sort of aggregated, citizen-science monitoring projects — especially when they’re designed so that the buy-in is low, both in terms of money spent and difficulty of getting your sensor online. This effort reminds us of Blitzortung, this radiation-monitoring network, or of the 2014 Hackaday-Prize-Winning SATNOGS. While we understand the need for expensive and calibrated equipment, it’s also interesting to see how far one can get with many many more cheap devices.

If you’d like to risk blowing your fingers off for a good cause this week, look no further than [M. Bindhammer]’s search for an eco-friendly rocket fuel. [M. Bindhammer] predicts the increasing use of solid rocket boosters in the future. We’re into that. For now, rocket launches are so few and far between that the pollution doesn’t add up, but when we’re shipping consumer electronics to the moon and back twice a day, we might have a problem.

The most common solid rocket fuel emits chlorine gas into the atmosphere when burned. [Bindhammer] is exploring safe ways to manufacture a eutectically balanced and stabilized fuel compromised of sugar or sugar-alcohol, and potassium nitrate. If you watch home chemistry videos for fun on the weekend like us, [Bindhammer] goes through all his thinking, and even spells out the process for duplicating his fuel safely in a lab.

He’s done a lot of work. The resulting fuel is stable, can be liquid or solid. It has a high ignition temperature, but as you can see in the video after the break. Once ignited. It goes off like rocket fuel.

Air quality is becoming a major issue these days, and not just for cities like Beijing and Los Angeles. It’s important for health, our environment, and our economy no matter where we live. To that end, [Radu] has been working on air quality monitors that will be widely deployed in order to give a high-resolution air quality picture, and he’s starting in his home city of Timisoara, Romania.

[Radu] built a similar device to measure background radiation (a 2014 Hackaday Prize Semifinalist), and another to measure air quality in several ways (a 2015 Hackaday Prize Finalist and a Best Product Finalist; winners will be announced next weekend). He is using the platforms as models for his new meter. The device will use a VOC air sensor and an optical dust sensor in a mobile unit connected to a car to gather data, and from that a heat map of air quality will be generated. There are also sensors for temperature, pressure, humidity, and background radiation. The backbone of the project is a smart phone which will upload the data to a server.

We’ve seen other air quality meters before as well, and even ones based around the Raspberry Pi, but this one has a much broader range of data that it is acquiring. Its ability to be implemented as an array of sensors to gather data for an entire city is impressive as well. We can envision sensor networks installed on public transportation but to get to all parts of every neighborhood it would be interesting to team up with the Google Streetview Cars, Uber, or UPS.

A while ago, [Joshua Young] had a conversation with an environmental scientist. There aren’t many government-funded pollution monitoring stations around Texas, but there are a lot of well-off home owners associations in Houston that have the sensors to collect the data. Air quality monitoring is important, and more data is usually better, and without these HOA’s providing the data for free, these environmental scientists wouldn’t have the data to do their job.

The system [Joshua] is building uses a suite of air quality sensors to measure sulfur dioxide, carbon monoxide, nitrogen oxides, ozone and particulate matter. These sensors connect to the Internet through either an ESP8266 WiFi module or a LoRa radio module, push the data onto the cloud, and let the entire world know what the air quality is.

Too much of a good thing can be a bad thing, and nitrate pollution due to agricultural fertilizer runoff is a major problem for both lakes and coastal waters. Assessing nitrate levels commercially is an expensive process that uses proprietary instruments and toxic reagents such as cadmium. But [Joshua Pearce] has recently developed an open-source photometer for nitrate field measurement that uses an enzyme from spinach and costs a mere $65USD to build.

The device itself is incredibly simple – a 3D printed enclosure houses an LED light source and a light sensor. The sample to be tested is mixed with a commercially available reagent kit based on the enzyme nitrate reductase, resulting in a characteristic color change proportional to the amount of nitrate present. The instrument reads the amount of light absorbed by the sample, and communicates the results to an Android device over a Bluetooth link.

Open-source instruments like this can really open up educational opportunities for STEM groups to get out into the real world and start making measurements that can make a difference. Not only can this enable citizen scientists and activists, but it also opens the door for getting farmers involved in controlling nitrate pollution at its source – knowing when a field has been fertilized enough can save a farmer unnecessary expense and reduce nitrate runoff.

There are a lot of other ways to put an open-source instrument like this to use in biohacking – photometery is a very common measuring modality in the life sciences, after all. We’ve seen similar instruments before, like a DIY spectrophotometer, or this 2015 Hackaday Prize entry medical tricorder with a built-in spectrophotometer. Still, for simplicity of build and potential impact, it’s hard to beat this instrument.

[Anirudh] and his friends were sitting around reminiscing about India. In particular, they recalled riding around in auto-rickshaws in stifling heat, watching their skin turn black from the exhaust. They started thinking about all of the soot and pollution in crowded cities the world over and wondered whether the stuff could be re-purposed for something like printer ink. That’s how they came up with their soot/pollution printer.

They created a soot-catching pump which they demonstrate with a burning candle. The pump mixes the soot particles with rubbing alcohol and an oil substrate and sends the ink to an HP C6602 inkjet cartridge. They used [Nicolas C Lewis]’s print head driver shield for Arduino to interface with the cartridge, turning it into a 96dpi printing head that uses only five pins.

[Anirudh] and his friends plan to design a carbon separator using charged plates to capture the soot particles from pollution sources and filter out dust. Be sure to check out their demonstration video after the jump.

Update: In response to [Hirudinea]’s comment about mining the carbon from cars, [Anirudh] is now looking for collaborators (tinkerers, filmmakers, DIY enthusiasts) to move forward with the idea of re-purposing carbon. Email him at anirudhs@mit.edu.

[Kasey] and [Guyzmo] have been working for the past couple of years on a side project that lets them monitor pollution using a network of sensors. They’ve just decided to make the project open source, both hardware and software. The details of the system are available at their GitHub repository.

There are two main components to the system. On the right is a base station which collects the data from the array of sensor, one of which is shown on the left. Each sensor runs off of a battery, but features a PV solar panel which keeps the power source topped off. It uses an Arduino to drive the system, and an XBee radio for communications. Some info about the sensors can be found on this summary page. There’s a PM10 particle pollution sensor, temperature, sound, nitrogen, and oxygen sensors. We also wonder if any data can be gleaned from how much electricity the solar panel is able to harvest?

The base station also uses an XBee radio to poll the network, but it’s not driven by an Arduino. They’ve gone with the ARM-based BeagleBone to manage the data.